1. Technical Field
This invention relates generally to valves for lines carrying water, sewage, natural gas, or other fluid, and more particularly to a valve and method for repairing a valve under pressure without first shutting down the line.
2. Description of Related Art
A typical valve may be manufactured from any of various materials, including ductile iron, cast iron, stainless steel, brass, plastics, and/or any of various exotic materials needed in special applications. The size can range from ¼-inch diameter or less to a 144-inch diameter or more. The valve may include a one-piece valve body with a hollow interior that extends between first and second ends of the valve body. The first and second ends are threaded, flanged, grooved, or otherwise configured so that a user can readily connect each end to a respective one of separate first and second pipeline sections, either directly or via intermediate fittings. In that regard, the term “pipeline” includes any type, size, and composition of fluid-carrying conduit, and the hollow valve body interior couples the first and second pipeline sections in fluid communications.
What is sometimes called a valve-stopping mechanism is mounted in the valve body. More specifically, part of the valve body defines an opening in the valve body that provides access to the hollow valve body interior. The valve-stopping mechanism is removably mounted within that opening in fluid-tight engagement of the valve body. There, it functions as means for enabling the user to selectively stop and unstop fluid communications between the first and second pipeline sections (i.e., between the first and second ends of the valve body). The opening in the valve body will subsequently be referred to as an “access opening,” and the portion of the valve body that defines the access opening will subsequently be referred to as an “opening-defining portion” of the valve body. The valve-stopping mechanism is sometimes called a user-operated, isolator mechanism or valving element. Known valve-stopping mechanisms include metal gate, rubber coated gate, butterfly, plug, ball, and check valve stopping mechanisms, each having its own special features and advantages. In addition, the hollow interior of the valve body may include mating surfaces cast into the body or attached to the body by known valve technology to create a seating surface for the valve-stopping mechanism. Attached materials may include brass, steel, stainless steel, plastics, and other known materials.
Regardless of the particular style of the valve-stopping mechanism, a valve is prone to becoming corroded, obstructed by mineral and/or chemical deposits or debris, or otherwise damaged to the point that it requires servicing in order to clean or resurface the hollow valve body interior and/or to clean, resurface, or replace the valve-stopping mechanism. The line may have to be shut down so that the valve is not under pressure. The valve is then serviced and afterwards the line is turned back on. However, the consequences of shutting down the line may be significant. For example, shutting down a municipal water main in order to service a branch line to a subdivision results in many inconvenienced and potentially monetarily damaged water customers.
Undertaking to shut down hospital systems, manufacturing plants, hotels, or nuclear facilities is also fraught with adverse consequences, including the cost of a plant shut down or the lack of fire protection during the shut down. The problem exists with gas valves, air valves, water valves, sewage valves, steam valves, any of numerous chemical valves, and other fluid valves for above ground and below ground pipe, including sub-sea systems. Thus, a need exists for a valve and repair method such that the valve can be installed when the pipe is installed and then serviced under pressure (i.e., with the valve containing fluid under pressure) without shutting down the line.